1. Field of the Invention
The present invention relates to image reading apparatuses that read an image of an original while transporting the original, to methods of controlling image reading apparatuses, and storage medium.
2. Description of the Related Art
Conventionally there are image reading apparatuses that use an automatic original transport device (automatic document feeder, hereinafter “ADF”) to carry out “flowing document reading” in which multiple originals are read. When a foreign substance such as dirt, dust, or an abrasion or smearing (hereinafter “dust”) adheres to a reading position of the original in the image reading apparatus, pixels in the area are distinguished as black pixels, thereby generating black streaks in the sub scanning direction (original feeding direction). As a technique for suppressing the generation of these black streaks, a technique relating to so-called dust correction in which dust adhering to a reading position of the original is detected and the black pixel data that has been generated by this dust is corrected in order to make the black streaks inconspicuous is known (Japanese Patent Laid-Open No. 2002-185725).
Dust detection is carried out immediately prior to reading each original, but there are cases where dust adheres to a reading position of the original while the original is being read. For example, there are cases where, during the reading of an original, dust that has adhered to the original then adheres onto a reading position at which a sensor reads the original. In this case, the detection of this adhered dust is carried out immediately prior to the reading of the next original after the original that was the cause of the dust adherence, and therefore dust correction can be carried out on the image data that has been read from the next original. However, the fact that dust correction cannot be carried out on the image data of the original that was the cause of the dust adherence during reading is a problem, as poor quality image data is obtained with black streaks remaining in the image data of the original.